论文标题
拉曼光谱法探测的ALN/SIC异源面的应力分布
Stress distribution at the AlN/SiC heterointerface probed by Raman spectroscopy
论文作者
论文摘要
我们通过物理蒸气沉积来生长Aln/4H-SIC和ALN/6H-SIC异质结构，并通过纳米级分辨率来表征异界面。此外，我们使用共聚焦拉曼光谱法研究了这些异质结构中的空间应力和应变分布。我们测量各种振动拉曼模式在杂项层以及4H和6H-SIC层的整个深度的光谱变化。使用对声子形成电位常数的早期实验预测，我们确定SIC中的应力张量成分是距ALN/SIC异源距离距离的函数。尽管SIC的晶格参数小于ALN的晶格参数，但SIC层在异源面上压缩。当异质结构从生长到室温冷却时，这种违反直觉的行为是通过SIC和ALN热膨胀系数的不同系数来解释的。压缩应力值最大在异源面上，接近一个GPA，并放松到异质方面几十微米的尺度上的平衡值。
We grow AlN/4H-SiC and AlN/6H-SiC heterostructures by physical vapor deposition and characterize the heterointerface with nanoscale resolution. Furthermore, we investigate the spatial stress and strain distribution in these heterostructures using confocal Raman spectroscopy. We measure the spectral shifts of various vibrational Raman modes across the heterointerface and along the entire depth of the 4H- and 6H-SiC layers. Using the earlier experimental prediction for the phonon-deformation potential constants, we determine the stress tensor components in SiC as a function of the distance from the AlN/SiC heterointerface. In spite that the lattice parameter of SiC is smaller than that of AlN, the SiC layers are compressively strained at the heterointerface. This counterintuitive behavior is explained by different coefficients of thermal expansion of SiC and AlN when the heterostructures are cooled from growth to room temperature. The compressive stress values are maximum at the heterointerface, approaching one GPa, and relaxes to the equilibrium value on the scale of several tens of microns from the heterointerface.
